Recently, uninhabited airborne vehicles that are called drones have been spread and used in various fields, for example, taking a picture from the sky and delivering packages. Although drones indicate all the uninhabited airborne vehicles, many are of multirotor types with a plurality of rotary wings as their main characteristics, which can control the direction and the altitude of the airframe and can be controlled by a communication method such as radio, Wi-Fi®, and Bluetooth®.
However, there are concerns that collisions between a drone and a person increase as the number of drones increases with the growing popularity of drones. Conventional drone control systems detect a person by an ultrasonic sensor that affects the rotary wings, and therefore inaccurately detect persons.
As a method of having a drone detecting an object by using a device other than an ultrasonic sensor, the sensor system of an uninhabited airborne vehicle that is provided with a photodetection and ranging system and a camera system to check the diameters of any number of trees in a group is proposed (Patent Document 1).